linux-kernel - Re: [PATCH] media: amphion: check and cancel vpu before release

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Message-ID: <5b77b349-16d2-e020-e4a7-43815088e1b8@xs4all.nl>
Date:   Fri, 18 Nov 2022 14:59:57 +0100
From:   Hans Verkuil <hverkuil-cisco@...all.nl>
To:     Ming Qian <ming.qian@....com>, mchehab@...nel.org
Cc:     shawnguo@...nel.org, robh+dt@...nel.org, s.hauer@...gutronix.de,
        kernel@...gutronix.de, festevam@...il.com, linux-imx@....com,
        xiahong.bao@....com, linux-media@...r.kernel.org,
        linux-kernel@...r.kernel.org, linux-arm-kernel@...ts.infradead.org
Subject: Re: [PATCH] media: amphion: check and cancel vpu before release

Hi Ming,

On 11/1/22 09:05, Ming Qian wrote:
> driver need to cancel vpu before releasing the vpu instance,
> but it doesn't want to release the m2m_ctx before
> the release callback of instance is called,
> as driver may access the m2m_ctx in handling some event
> which may be received in releasing instance.
> 
> check and cancel the unstopped instance before release.
> 
> Fixes: d91d7bc85062 ("media: amphion: release m2m ctx when releasing vpu instance")
> Signed-off-by: Ming Qian <ming.qian@....com>
> ---
>  drivers/media/platform/amphion/vpu_v4l2.c | 18 ++++++++++++++++++
>  1 file changed, 18 insertions(+)
> 
> diff --git a/drivers/media/platform/amphion/vpu_v4l2.c b/drivers/media/platform/amphion/vpu_v4l2.c
> index 99ad2f1c5a53..845fc53d8937 100644
> --- a/drivers/media/platform/amphion/vpu_v4l2.c
> +++ b/drivers/media/platform/amphion/vpu_v4l2.c
> @@ -767,6 +767,23 @@ int vpu_v4l2_open(struct file *file, struct vpu_inst *inst)
>  	return ret;
>  }
>  
> +static void vpu_v4l2_check_and_cancel(struct file *file, struct vpu_inst *inst)
> +{
> +	struct vb2_queue *vq;
> +
> +	vpu_inst_lock(inst);
> +
> +	vq = v4l2_m2m_get_src_vq(inst->fh.m2m_ctx);
> +	if (vb2_is_streaming(vq))
> +		v4l2_m2m_streamoff(file, inst->fh.m2m_ctx, vq->type);
> +
> +	vq = v4l2_m2m_get_dst_vq(inst->fh.m2m_ctx);
> +	if (vb2_is_streaming(vq))
> +		v4l2_m2m_streamoff(file, inst->fh.m2m_ctx, vq->type);
> +
> +	vpu_inst_unlock(inst);

This feels weird. This is normally done in v4l2_m2m_ctx_release(), so
if you need to do this here, doesn't that mean perhaps that the order
of releasing things should be changed? I.e., first call v4l2_m2m_ctx_release()
and only afterwards release the vpu instance.

In other words, are you just fixing the symptom rather than the actual
cause?

Regards,

	Hans

> +}
> +
>  int vpu_v4l2_close(struct file *file)
>  {
>  	struct vpu_dev *vpu = video_drvdata(file);
> @@ -774,6 +791,7 @@ int vpu_v4l2_close(struct file *file)
>  
>  	vpu_trace(vpu->dev, "tgid = %d, pid = %d, inst = %p\n", inst->tgid, inst->pid, inst);
>  
> +	vpu_v4l2_check_and_cancel(file, inst);
>  	call_void_vop(inst, release);
>  	vpu_inst_unregister(inst);
>  	vpu_inst_put(inst);